Chapter 20 Flashcards
The Heart
what is the fundamental function of the heart?
the heart acts as a pump, producing the force that causes blood to circulate
what is the pericardium and what is it made up of?
a sac that surrounds the heart
consists of the fibrous and the serous pericardium
what is the function of the fibrous pericardium?
it helps hold the heart in place
what is the function of the serous pericardium?
it reduces friction as the heart beats
what does the serous pericardium consist of?
the parietal pericardium, visceral pericardium and pericardial cavity
name the 3 layers of the heart wall
the outer epicardium (visceral pericardium), the middle myocardium and inner endocardium
describe the functions of each layer of the heart
outer epicardium- provides protection against friction of rubbing organs
middle myocardium- responsible for contraction
inner endocardium- reduces friction from blood passing through heart
the muscular ridges in auricles are called:
pectinate muscles
the muscular ridges in ventricles are called:
trabeculae carneae
an atrial flap is called:
an auricle
what separates the atria from the ventricles?
the coronary sulcus
what structures enter the right atrium?
inferior and superior vena cavae
coronary sinus
what structures enter the left atrium?
the four pulmonary veins
what structures exit the right and left ventricles respectively?
right ventricle- pulmonary artery
left ventricle- aorta
what structures separate the atria and ventricles from one another?
atria- the interatrial septum
ventricles- the interventricular septum
which valve separates the right atrium from the right ventricle?
the tricuspid valve
which valve separates the left atrium from the left ventricle?
the bicuspid/mitral valve
how are muscles attached to the atrioventricular valves?
the chordae tendineae
attach the papillary muscles
to the atrioventricular valves
which valves separate the aorta and pulmonary trunk from the ventricles?
the semilunar valves
what is the route of blood flow of blood from the body?
vena cavae, right atrium, right ventricle, pulmonary artery, lungs
what is the route of blood flow from the lungs?
pulmonary vein, left atrium, left ventricle, aorta, body
list some key histological features of cardiac muscle
-branched and striated
-centrally located nucleus
-actin and myosin organised to form sarcomeres
-cells joined by intercalated disks
-APs pass from one cell to another through gap junctions
-well supplied with blood vessels
-aerobically respire to form ATP
where are the SA (sinoatrial) and AV (atrioventricular) nodes located?
in the right atrium
how is the AV node connected to the bundle branches in the interventricular septum?
by the AV bundle
what structure do the bundle branches give rise to?
the Purkinje fibers
list the key structure of the heart in the order an action potential passes through them
-SA node
-AVN
-Bundle of His
-Purkinje fibres
the term for the spontaneous development of a pacemaker potential from cardiac pacemaker muscle cells is:
autorhythmic
the pacemaker potential results from the movement of:
sodium and calcium into the pacemaker cells
what are ectopic foci?
areas of the heart that regulate heart rate under abnormal conditions
the movement of which ions cause depolarisation in cardiac muscle cells?
sodium ions through voltage-gated sodium channels
which voltage-gated channels are open and closed during depolarisation of a cardiac muscle cell?
-sodium channels open
-potassium channels closed
-calcium channels begin to open
repolarisation of a cardiac muscle cell is the result of:
closure of VG sodium channels and opening of VG potassium channels
why does the plateau during an action potential in a cardiac muscle cell exist?
voltage gated calcium channels remain open
rapid repolarisation results from:
closure of VG calcium channels and opening of some VG potassium channels
the entry of calcium into cardiac muscle cells causes:
calcium to be released from the sarcoplasmic reticulum to cause contractions
cardiac muscle has prolonged depolarisation and thus a prolonged refractory period. what does this allow for?
allows the cardiac muscle time to relax before the next action potential causes a contraction
an ECG records:
the electrical activity of the heart
which phase produces the P wave?
depolarisation of the atria
which phase produces the QRS complex?
depolarisation of the ventricles
repolarisation of the atria occurs during:
the QRS complex
which phase produces the T wave?
repolarisation of the ventricles
ECGs can be used to diagnose heart abnormalities based on:
-magnitude of ECG waves
-time between waves
an ECG would not be able to diagnose a heart murmur because:
heart murmurs are detected by listening to heart sounds
activity in which valves cause the 1st heart sound?
closure of the atrioventricular valves
activity in which valves cause the 2nd heart sound?
closure of the semilunar valves
a 3rd heart sound may be produced due to:
turbulent flow of blood into the ventricles
mean arterial blood pressure is:
the average blood pressure in the aorta
mean arterial pressure is proportional to:
cardiac output x peripheral resistance
define cardiac output
amount of blood pumped by the heart per minute
define peripheral resistance
total resistance to blood flow through blood vessels
cardiac output is equal to:
stroke volume x heart rate
define stroke volume
amount of blood pumped by the heart per beat
stroke volume is equal to:
end diastolic volume - end systolic volume
how does increased venous return increase stroke volume?
by increasing end diastolic volume
how does increased force of contraction increase stroke volume?
by decreasing end systolic volume
what is cardiac reserve?
the difference between resting and exercising cardiac output
what is venous return?
the amount of blood that returns to the heart during each cardiac cycle
what does the Starling Law of the heart describe?
the relationship between preload and the stroke volume of the heart
which part of the brain regulates parasympathetic and sympathetic nervous control of the heart?
the cardioregulatory center in the medulla oblongata
parasympathetic stimulation is supplied by:
the vagus nerve
how does parasympathetic stimulation affect heart rate?
decreases heart rate
describe parasympathetic stimulation’s role in heart regulation
-postganglionic neurons secrete ACh (acetylcholine)
-increases membrane permeability to potassium
-causes hyperpolarisation of the membrane
sympathetic simulation is supplied by:
the cardiac nerves
how does sympathetic stimulation affect heart rate?
increases heart rate (as well as force of contraction/stroke volume)
describe sympathetic stimulation’s role in heart regulation
-postganglionic neurons secrete norepinephrine
-increases membrane permeability to sodium and calcium
-causes depolarisation of the membrane
from which location are epinephrine and norepinephrine released?
into the blood from the adrenal medulla
how do epinephrine and norepinephrine affect the heart?
-increase heart rate and force of contraction
-long-lasting effects compared to neural stimulation
what do baroreceptors monitor?
blood pressure
how do baroreceptors respond to a decrease in blood pressure?
-increase sympathetic stimulation
-decrease parasympathetic stimulation
-increasing heart rate and force of contraction
what do chemoreceptors monitor?
-blood CO2 levels
-blood O2 levels
-blood pH levels
how do medullary chemoreceptors respond to increased blood CO2 and decreased blood pH?
-increase sympathetic stimulation
-decrease parasympathetic stimulation
which type of chemoreceptor is stimulated by low O2 levels and what does this result in?
-carotid body chemoreceptor
-result in decreased heart rate and vasoconstriction
what is the effect of an increase or decrease in extracellular potassium on heart rate?
decreased heart rate
what are the effects of increased extracellular calcium on the heart?
-increased force of contraction
-decreased heart rate
what are the effects of body temperature on heart rate?
-increased temperature increased heart rate
-decreased temperature decreased heart rate
